/**
 * Copyright (C) 2015 lib
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package diandiansong.library.tabviewpager.utilsv4;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.util.SparseArrayCompat;
import android.view.ViewGroup;

import java.lang.ref.WeakReference;


public class FragmentPagerItemAdapter extends FragmentPagerAdapter {

 private final FragmentPagerItems pages;
 private final SparseArrayCompat<WeakReference<Fragment>> holder;

 public FragmentPagerItemAdapter(FragmentManager fm, FragmentPagerItems pages) {
   super(fm);
   this.pages = pages;
   this.holder = new SparseArrayCompat<>(pages.size());
 }

 @Override
 public int getCount() {
   return pages.size();
 }

 @Override
 public Fragment getItem(int position) {
   return getPagerItem(position).instantiate(pages.getContext(), position);
 }

 @Override
 public Object instantiateItem(ViewGroup container, int position) {
   Object item = super.instantiateItem(container, position);
   if (item instanceof Fragment) {
     holder.put(position, new WeakReference<Fragment>((Fragment) item));
   }
   return item;
 }

 @Override
 public void destroyItem(ViewGroup container, int position, Object object) {
   holder.remove(position);
   super.destroyItem(container, position, object);
 }

 @Override
 public CharSequence getPageTitle(int position) {
   return getPagerItem(position).getTitle();
 }

 @Override
 public float getPageWidth(int position) {
   return super.getPageWidth(position);
 }

 public Fragment getPage(int position) {
   final WeakReference<Fragment> weakRefItem = holder.get(position);
   return (weakRefItem != null) ? weakRefItem.get() : null;
 }

 protected FragmentPagerItem getPagerItem(int position) {
   return pages.get(position);
 }

}
